Organic-inorganic hybrid perovskite materials such as perovskite halides have emerged as one of the most promising light absorbers due to their superior optoelectronic properties. Hybrid perovskites based photovoltaics outperform a significant number of the currently mature photovoltaic technologies and can provide power conversion efficiencies of greater than 20%. They have tunable bandgap, experience rapid dissociation of carriers at room temperature, exhibit high carrier mobility and can absorb lights having wavelengths in the entire visible spectrum.
For photovoltaic devices, in particular, an important prerequisite is the long term stability against ambient moisture and temperature. An intrinsic challenge in device application of hybrid perovskites, however, is the long-term stability. The presence of a hygroscopic ionic small molecules, (i.e. alkylammonium cations), has been identified as the culprit for the sensitive nature of hybrid perovskites towards moisture and temperature, particularly to relative humidity (RH) above 35% RH and temperatures above 150 degrees Celsius or 200 degrees Celsius (depending on the particular perovskite halide), respectively. This has prevented the widespread use of the hybrid perovskites in devices such as solar cells, LEDs and other applications.